I'm here to discuss about the possible reasons to why Rena Rouge's body structure differentiates to her usual body reference models; particularly her reference models for Alya and Lady Wifi.
Rena Rouge's body proportions is slightly different compared to Ladybug's and Cat Noir's outfits. Her body proportions as a superhero is way different to her body shape as Alya. Rena's tummy and hip (is cute) but seems to be slimmer than Alya's. Lady Wifi's model base seems to coordinate with Alya's. Both reference models of Alya and Lady Wifi look identical, and you can tell by looking at her face structure, chest, stomach, hips, and legs which all seem aligned together. It seems like ZAG substantially had much more time in those days to ensure that the body extents and structure for their characters stay consistent together.
Then again, Rena's body structure doesn't look symmetrical as compared to her other previous models. Her face looks more round, and her body is slimmer. This is probably due to the show staff not being able to relocate her older body model to use for reference, and instead opted to utilize an frequent and all the more effectively available one. It is speculated that Rena Rouge's body show is reused with Volpina's model, henceforth both Volpina and Rena share similarities with their body structure.
As with Rena's domino mask, I find that really strange and unsettling, especially since it makes her mask looks oddly proportioned. It seems like her mask doesn't fit comfortable on her face, and it looks strange to me. Rena having a domino mask (not essentially covering her eyelids) and her weird inconsistent body proportions was must likely not intentional. To the extent I'm mindful, neither Sapotis or Syren were animated by SAMG. The former was animated by Method Studios (Who is in partnership with SAMG and ZAG studios and they own DQ animation) and the latter was worked by DQ. You can tell by the surreal look Rena has in Syren.
Here, Rena reminds me of one those circus babies from FNAF. No seriously, I had nightmares and it was not pretty.
The last time I had a nightmare of FNAF was looking at this screenshot of Hawk Moth. Dude bought up memories of The Puppet from FNAF too.
Anyway, back on topic.
In an not-to-old conceptualised image of Alya, you can see her intended body model, you can see her expected body display, which I assume is what she's really expected to look like in the show. Method must have tried their hardest and rushed to get this episode done as soon as possible. So lets give credit to them because creating new body designs, let alone rendering them is very difficult, and I'm certain Method attempted their absolute best to influence Rena to look as normal as would be natural and stylish.
Furthermore, SAMG has recently released new CGI models of the superheroes, which some include RR and their models of Alya are more visually stunning which I then noticed that it looks different to Method and DQ's reference models. With how SAMG re-designing RR's body proportions, you can see that her mask is actually fixed, laying serenely all over and it covers her eyelids, like Ladybug's and Cat Noir's covers. YAY! Although, Her stomach is still marginally slim though, but it looks so much more natural and much more accentuated. which I prefer.
There are many images of RR's CGI model rendered by SAMG.
Hopefully, if SAMG contributes to episodes that Rena Rouge may potentially appear in, there is a possibility that the team will use their own body references and fix Rena's design, giving us the opportunity see her intended superhero design and witness her more prominent, visually stunning, beautiful and polished and gives a more natural look to Alya, which i'm excited to see!